The mystery of the missing atmosphere of Mars was a step closer to its solution. The previous hypothesis suggested that a significant portion of carbon from the atmosphere of Mars, in which carbon dioxide predominates, can be fixed between rocks by chemical processes. However, a new study suggests that there is not enough carbon in the sediments on the surface of the Red Planet, given the huge amount lost from the air over a long period of time.
“The largest carbon deposition on Mars is, at best, twice as much carbon as the current atmosphere of Mars,” said study co-author Bethany Ehlmann of the California Institute of Technology (Caltech) and NASA's Jet Propulsion Laboratory in Pasadena, California.
“Even if you combine all the known carbon reservoirs together, it will still not be enough to isolate the thick atmosphere that was proposed for the time when there were rivers flowing on the surface of Mars,” added Ehlmann, who worked with lead author Christopher. Edwards, a former researcher at the California Institute of Technology (now with the US Geological Survey).
Although Mars is dry today, scientists believe that the surface of the planet contained large volumes of fluid billions of years ago. Then, in the past, Mars had to have a much thicker atmosphere in order to save water from freezing or instantaneous evaporation, scientists say. (Atmosphere of Mars currently makes up only 1 percent of the thickness of the Earth’s atmosphere at sea level). Carbon dioxide can be extracted from the atmosphere by chemical reactions with rocks, forming carbon minerals. A previous study suggested that the Red Planet could be covered with significant carbon deposits that could be saved before Mars lost its atmosphere.
But the orbiters of Mars and the rovers found only a few concentrated carbon deposits. The most famous carbon-rich deposition on Mars is the Neil Foss region, which is not less than Delaware size and potentially as large as Arizona.
Edwards and Ehlmann used data from numerous missions to Mars, including NASA's Mars Global Surveyor, Mars exploration orbit, and Mars Odyssey orbit to estimate how much carbon is locked in Nile Foss. Then they compared this amount with the one they need to form a dense, carbon-rich atmosphere that would contribute to the existence of water on the surface while rivers flow, which have a wide carved valley of networks on the surface of the planet.
Results? More than 35 carbon deposits of the size of Nili Foss require the isolation of a large amount of carbon as the atmosphere of Mars, which he probably already lost.
The surface of Mars was widely probed by orbits and vehicles, revealing only limited and isolated carbon deposits. Thus, Edwards and Ehlmann consider it unlikely that so many large deposits remained closed after the last test. Although very early sediments may be hidden under the Martian crust, their existence does not reveal the secret of the atmosphere that existed when a river-carved valley was formed. So, if the thick atmosphere was not locked in carbon deposits, what happened to it? One possibility is that it could be lost in space from the upper atmosphere — a phenomenon that NASA’s Curiosity rover found evidence in the past.
However, scientists are not sure how much of what is lost happened before the formation of the valleys. NASA's MAVEN (Mars Atmosphere and Volatile Evolution) orbiter can help narrow the mystery, as it studies the atmosphere of Mars.
Maybe the atmosphere was not so thick at the time of the formation of the network of valleys, ”said Edwards. “Instead of Mars being wet and warm, maybe it was cold and wet, an atmosphere that has already thinned out. What heat is needed for valleys to form? Not very warm. ”
“In most places you could have snow and ice instead of rain,” said Edwards. “You just have to push above the freezing point to thaw the water, and it doesn't require a lot of atmosphere.” The study was published online August 21 in the journal “Geology”.